feat: show pending and failed outgoing transactions

[rolznz]

Fixes #426

Failed and unsettled outgoing transactions are now shown in the transaction list. Pending transactions have a pulse animation.

I also added an alert on the send page if the user has any pending payments, to avoid the chance they accidentally try pay again.

Note: Listing transactions is now ordered by updated_at rather than settled_at, created_at

TODOs:

• fix ordering (settled at is an issue for unpaid payments)
• should transactions that have expired (unsettled after expiration of the invoice) be updated to failed?
• support params for NIP-47 so Alby Go can do the same

[rolznz]

I've also updated #380 which I think we need two things:

• splitting unpaid into outgoing and incoming
• including the transaction state in the transaction object (settled, pending, failed)